1. Field of the Invention
This invention relates generally to energy saving apparatus and more particularly to an electronic energy saving override control apparatus for room heating and cooling systems.
2. Description of the Prior Art
Power temperature control devices have long been known in the art for controlling the temperature of a specified enclosed area. Such systems typically employ at least one temperature control sensor or thermostat to provide a power regulating control signal to a primary heating and/or cooling unit, to maintain the controlled temperature within a predetermined temperature comfort range. Traditionally, the predetermined range has varied within several degrees on either side of a median temperature setting which is manually adjustable by an occupant of the temperature controlled area to satisfy that occupant's comfort needs.
It has long been recognized that considerable savings in energy consumed by such heating/cooling units can be achieved by setting the selected temperature to a value which is outside of the normally desired comfort temperature range when the controlled area will be unoccupied or would not require the more accurately controlled temperature range. For example, it is well know that significant energy savings can be achieved for a heating unit if the temperature control setting for the heating unit is set back or down to 60.degree. or 65.degree. F. during the evening hours in which the occupants of the temperature controlled area are normally sleeping. Conversely, energing savings can be achieved with air conditioning units by setting the air conditioning temperature control up or forward to a higher than normal temperature setting (for example to 80.degree. F.) during those extended periods of time during which the temperature controlled area will be unoccupied.
Early such energy saving techniques required the occupant of the temperature controlled area to manually set the thermostat control to the lower or higher energy saving level respectively upon retiring or leaving respectively the temperature controlled area. Mechanized timing devices having integrated clockwork mechanisms were later incorporated into thermostat control devices for automatically setting back temperature settings at predetermined times of the day which were theoretically designed to coincide with the normal sleeping hours of the occupants of the temperature controlled area. Such devices are convenient for use in residential temperature control environments where the daily schedule of the occupants within the temperature controlled area is relatively fixed, but are inflexible, cumbersome and generally unsatisfactory for use in commercial environments such as in hotels and motels having a large number of guest rooms, each having its own independently controlled heating and cooling unit and wherein the guest occupancy conditions are continuously changing.
In attempting to more accurately relate the temperature set back control feature with the active occupancy of the temperature controlled area, later temperature set back control devices were configured which operated in response to the ambient illumination level within the temperature controlled area. Such devices typically provided normal comfort control signals to the primary heating unit of the room as long as the illumination intensity of the controlled area was maintained above a predetermined threshold level, typically satisfied by illumination through the windows during daylight hours and by electric lighting during evening hours. Such devices operate on the implied assumption that the occupant of the controlled area will maintain a certain predetermined threshold of illumination within the room during his waking hours. Such devices, however, have no provision for regulating the temperature within the temperature controlled area at a non-comfort setting during the daylight hours of a day if, for example, the temperature controlled area were to remain unoccupied for extended periods of time during the daylight hours, as is typically the case in hotel and motel guest rooms. Also, if the room occupant were to leave a light on within the controlled area after leaving the area, the temperature control device would maintain the higher energy consuming comfort level of the controlled area during the evening hours even though the room was unoccupied. Further, such temperature set back control devices are typically inappropriate for use as energy saving devices with air conditioning units since they would require the occupant of a controlled area to maintain a light in an illuminating mode of operation within the controlled area while he were asleep, if he desired the air conditioning unit to maintain the preset comfort temperature level during the evening hours.
The present invention overcomes the shortcomings and deficiencies of the prior art temperature set back control devices by providing a simple, efficient, flexible and highly reliable energy saving control apparatus particularly suitable for application in combination with individual room heating and cooling units such as used in hotels and motels. The energy saving control apparatus of this invention is adaptable to use with any thermostat controlled heating and/or cooling unit and responds to a positive input signal applied by the occupant of the room, in a manner which assures operation of the heating/cooling unit of the controlled area within the normal comfort temperature range while the occupant is within the temperature controlled area, but maximizes energy saving operation of the heating/cooling unit whenever the occupant is not within the temperature controlled area.